Most people who start doing cardio do long, mind-numbing hours on a treadmill or bike. It’s not hard to see why people take this approach – it’s what everyone else seems to be doing at the gym. It also seems intuitive – after all, if you want to lose weight you have to put in your time, right?
When it comes to cardio for the purpose of fat loss, the most effective method is actually the least intuitive – going on shorter, but higher intensity sprints is significantly better for weight loss than long, steady jogs. This method of sprinting for weight loss is known as high intensity interval training, or HIIT.
So what exactly is high intensity interval training, and why is it preferable to longer, steady periods of cardio? If we take running as an example, the typical jogger will pace themselves at a steady clip over a fixed distance or period of time. If the jogger is planning to run for an hour, they jog at a pace they can sustain for an hour.
HIIT training on the other hand would involve doing short – but intense – sprints where the runner runs as fast as they possibly can. On the treadmill, this might mean cranking up the incline and increasing the speed drastically. While the period of exercise is short – usually 15-60 seconds – the individual pushes themselves as hard as they can during that short interval.
After the sprint, the person takes a short break before repeating another all-out interval, and then another, until they’re fully exhausted. The total exercise time is usually no more than 10-20 minutes. HIIT training takes less time to achieve the same results as longer, slower running – but it’s certainly not easier.
But how do we know that sprinting combined with interval training is more effective for fat loss than a steady jog? A study in International Journal Sport Nutrition and Exercise Metabolism divided two groups of male students and assigned them to do either 30 minutes of steady jogging, or 2 minutes of intensive sprint interval training – 3 times a week for 6 weeks. Researchers found that the interval spring training actually boosted the student’s metabolism the same amount as those who jogged, even though the joggers exercised for 28 minutes more than the sprinters each session. This was just one of many studies.
Why is this sort of sprint training superior to longer, marathon style runs for weight loss? Here are a few reasons:
There is an anabolic effect – Research has shown that doing sprint training along with eating more calories can actually help you build muscle, which in turn burns more fat even when you’re inactive. Have you never noticed a sprinter’s build compared to a marathon runner? The anabolic effect is a factor (though certainly not the only factor) in that striking body difference.
Increased Aerobic capacity – Doing intense sprints that push your body’s systems to the limit increases the amount of oxygen your body can use. You’ll feel more energized and “fit” from doing sprints, compared to doing long, but low intensity cardiovascular exercise.
Increased Insulin Sensitivity – High intensity interval training causes your muscle groups to absorb glucose more readily, preventing it from being stored as fat.
Afterburn Effect – Doing interval training creates what some fitness experts have called the “afterburn effect”. While the physiology of the effect is complicated to describe, in a nutshell, the intense sprinting kicks the body’s metabolism into high gear, helping you burn off fat even 24-48 hours after your last workout.
Less hunger – Long, slow, steady cardio tends to make you more hungry than sprint training. Joggers tend to find themselves famished after a long run, whereas high intensity interval sprints have little effect on appetite. This effect is related to the way long low intensity training affects insulin levels
But perhaps you might ask, what about the “fat burning zone”? For years, the conventional wisdom has been that keeping a slow, steady pace during cardio was better for losing fat. This flawed wisdom was based on research which showed that low intensity training is more likely to use stored fat as fuel than high intensity sprints, which tends to rely on glycogen for energy.
While this is certainly true, the reason this wisdom is flawed is because the high intensity training still results in more fat burned overall, even if the lower intensity training burned more fat compared to glycogen percentage wise.
This certainly doesn’t mean that you should avoid going for a jog around the neighborhood or hopping onto the treadmill for 45 minutes if you want to. On the contrary, for overweight or obese individuals, it’s essential to start building up a cardio base through jogging before you begin high intensity interval training. Many people also find going on long runs calming, almost meditative. And of course, going on long runs does burn calories, even if it doesn’t do so as efficiently as high intensity interval training. However, if you’re looking to burn fat efficiently, your best bet is to stop jogging and start doing HIIT.